Studies of the transcriptional and translational events which lead to the induction of various forms of cytochrome P-450 by inducing agents such as phenobarbital and 3-methylcholanthrene are underway. As it has been shown in this laboratory and others that administration of such inducing agents leads to increased in vitro synthesis of specific forms of cytochrome P-450, attempts will be made to isolate mRNA samples which are enriched for the phenobarbital and 3-methylcholanthrene inducible forms of cytochrome P-450. These will be utilized in the preparation of specific cDNA probes for these two forms of cytochrome P-450. Hybridization studies with such probes will be carried out in order to determine whether induction leads to increased levels of specific mRNA species which code for a particular form of cytochrome P-450. In addition, studies of the induction of cholesterol side chain cleavage cytochrome P-450 (P-450scc) by ACTH will be carried out in monolayer cultures of bovine adrenal cortical cells. It will be determined whether administration of ACTH to such cell cultures leads to increased in vitro synthesis of this form of cytochrome P-450, and if so, what the temporal profile for this phenomenon might be.